1. Field of the Invention
The present invention relates to a data converting or processing apparatus adapted to convert stored original outline data representative of letters, numerals, symbols and other characters, into normal outline data usable for outputting the characters. More particularly, the present invention is concerned with a technique for partially compressing or abridging character outline data for reduction in required data storage capacity, and converting the abridged character outline data into the normal character outline data.
2. Discussion of the Prior Art
An apparatus for processing character outline data is used, for example, for character output devices such as a printer for printing characters on a recording medium, and a display device for displaying the characters on a display screen. An example of such a character output device includes (a) an outline data memory storing a batch of outline data representative of outlines of strokes of a multiplicity of characters, each character consisting of one or more strokes, and each stroke consisting of a plurality of segments which constitute a closed loop, (b) data converting means for converting the outline data into corresponding dot data representative of image dots defining each character, (c) means for retrieving from the outline data memory the outline data representative of desired characters that are to be printed, displayed or otherwise outputted on an appropriate output medium such as a recording medium or display screen, and supplying the retrieved outline data to the data converting means, and (d) character output means for outputting the characters according to the dot data prepared from the retrieved outline data by the data converting means.
In such a known character output device, the outline of each stroke of each character consists of a plurality of segments (straight or curved lines), each of which is represented by a set of segment data stored in the outline data memory. Thus, each segment of a stroke of a character is defined by an appropriate set of segment data, which is stored as a unit in the outline data memory.
However, a research by the present applicants indicated that storing the character outline data in the form of segment data sets representative of all individual segments of each stroke of the character is not necessarily desirable. In other words, the applicants found it desirable, in some cases, to store the character outline data such that data representative of a certain number of successive segments of a character stroke are stored as a unit.
The outline data for Chinese characters of "mincho" type style is one example of the above cases. In the "mincho" type style, some strokes of the same character or different characters have ornamental portions (as illustrated in FIG. 5) such as serifs which are similar in shape to each other. Such similar ornamental portions of different strokes may be represented by a basic ornamental pattern whose outline (open outline) is defined by basic pattern data consisting of sets of segment chain data representative of a chain of segments. If this basic pattern data are stored in a given memory, segment data sets representative of the similar ornamental portions of the different strokes can be obtained by modifying the basic pattern data (segment chain data) according to the specific size of the individual common ornamental portions. This arrangement eliminates the need of storing in the outline data memory the segment data sets which represent the similar ornamental portions of the different strokes which have the same or different sizes. Accordingly, the capacity of the outline data memory required to store the outline data for a certain number of "mincho" type style Chinese characters can be reduced as compared with the conventionally required memory capacity. Namely, the outline data processing apparatus can use an outline data memory having a reduced storage capacity.